Hearing aid prostheses, such as those designed to be worn behind the ear of the recipient, commonly referred to as behind-the-ear (BTE) devices, may be components of conventional hearing aids, cochlear implants, and/or the like. BTE devices, whether implemented as a component of a hearing aid, cochlear implant, middle ear implant or other hearing prosthesis, are collectively and generally referred to herein as a BTE prosthetic devices.
Conventional hearing aids may include external sound processors which input the processed (and amplified) sound in the ear by an external, or in-the ear speaker. Cochlear implants have been developed to assist people who are profoundly deaf or severely hearing impaired, by enabling them to experience a hearing sensation representative of the natural hearing sensation. In most such cases, these individuals have an absence of or destruction of the hair cells in the cochlea which naturally transduce acoustic signals into nerve impulses which are interpreted by the brain as sound. The cochlear implant therefore bypasses the hair cells to directly deliver electrical stimulation to the auditory nerves with this electrical stimulation being representative of the sound.
Cochlear implants have traditionally comprised two parts, an external component and an implanted receiver/stimulator unit. The external component may be been worn on the body of a recipient, classically as a BTE prosthetic device. The purpose of such a BTE prosthetic device has been to detect external sound using a microphone and convert the detected sound into a coded signal through an appropriate speech processing strategy.
This coded signal is then sent via a transcutaneous link to receiver/stimulator unit which is implanted in the mastoid bone of the recipient. A transcutaneous link is a magnetic induction link between a coil antenna of the implant and an externally applied coil antenna. The receiver/stimulator unit processes the coded signal into a series of stimulation sequences which are then applied directly to the auditory nerve via a series of electrodes positioned within the cochlea proximal to the modiolus of the cochlea.
The externally applied coil antenna typically forms part of a headpiece, which is applied in close proximity of the coil antenna of the implant and is connected to an external speech processor, such as a device for behind the ear. The magnetic induction link (established in a reactive near-field) typically allows bidirectional communication and power transfer towards the implant.